Article Figures & Data
Figures
- Figure 1.
Nicotine self-administration and extinction. A, A timeline of experimental procedures. JVC, jugular vein catheterization; RST, reinstatement. B, Rats acquired nicotine self-administration, distinguishing between active (red) and inactive (gray) levers to receive intravenous infusions of nicotine (black). Active lever pressing was reduced across extinction sessions; #p < 0.05 represents a main effect of session on active lever pressing. The vertical dotted line in B separates self-administration sessions and extinction sessions.
- Figure 2.
Male and female rats did not differ in nicotine self-administration or extinction of lever pressing. No differences were found between male and female rats in active (A) or inactive (B) lever pressing throughout self-administration. Additionally, they did not differ in the number of infusions across self-administration sessions (C) or the total number of nicotine infusions earned throughout the 10 non-consecutive criteria-making sessions (D). Data points within D represent individual animal values. Males and females did not differ in active (E) or inactive (F) lever pressing throughout extinction. Male and female rats are depicted in black and gray, respectively. Numbers in legend of panel A represent the number of animals in each group.
- Figure 3.
Control, excitatory, and inhibitory DREADD-expressing animals did not differ in rates of nicotine self-administration or extinction lever pressing. Regardless of the type of DREADD expression, animals showed no difference in active (A) or inactive (B) lever pressing throughout self-administration. Additionally, animals not differ in the number of infusions across self-administration sessions (C) or the total number of nicotine infusions earned throughout the 10 non-consecutive criteria-making sessions (D). Data points within D represent individual animal values. DREADD groups did not differ in active (E) or inactive (F) lever pressing throughout extinction. Control, excitatory and inhibitory DREADD-expressing rats are depicted in black, green, and red, respectively. Numbers in legend of panel A represent the number of animals in each group.
- Figure 4.
Chemogenetic ChI inhibition prevented cue-induced nicotine seeking and reduced A/N ratio. A, The DREADD constructs used in the current study readily express mCherry in neurons (left panel). ChAT labeled cell bodies within the NAcore (middle panel), which co-expressed with all mCherry labeled neurons (right panel). Arrows depict cell bodies. Scale bar: 30 μm. B, CNO bath application had no effect on control virus expressing ChIs (top; black), promoted firing in the excitatory DREADD-expressing ChI (middle; green); and blunted firing in the inhibitory DREADD-expressing ChI (bottom; red). C, In control and excitatory DREADD-expressing animals, active lever pressing was increased during cue-induced reinstatement compared with extinction following intra-NAcore CNO treatment. In animals expressing the inhibitory DREADD, CNO inhibition of ChIs prevented cue-induced nicotine reinstatement, where active lever pressing during reinstatement was not different from extinction; *p < 0.05 versus extinction, **p < 0.01 versus extinction; n.s., non-significant. Inset numbers represent number of animals. D, A/N ratio was reduced in animals with ChI inhibition following reinstatement [T(time) = 15] relative to control DREADD-expressing animals. The inset numbers within D represent number of animals with the total number of cells recorded from within parentheses. Representative AMPA and NMDA traces for each DREADD type is shown in panel E. A picture depicting the NAcore and stimulating electrode placement is also shown. Numbers in bars represent animal number and numbers in parentheses represent the total number of cells. Data points within C, D represent individual animal values. Scale bars (x, y): 50 ms, 100 pA; **p < 0.01.
- Figure 5.
Cellular capacitance, resting membrane potential and NMDA decay time did not differ between DREADD-expressing groups. Cellular capacitance (A), resting membrane potential (B), and NMDA decay to 37% of the peak amplitude (C) did not differ between control, excitatory, or inhibitory DREADD-expressing animals following cue-induced reinstatement. The inset numbers represent number of animals with the total number of cells recorded from within parentheses. Data points within represent individual animal values.
- Figure 6.
Active lever presses during reinstatement was positively correlated with MSN A/N ratio. The number of active lever presses and A/N ratio for each animal is shown. The number of animals plotted for each group is depicted as N within the figure. The A/N ratio measured for each cell was averaged across all cells from the same animal (between one and four cells/animal) to obtain the A/N for each animal which was then compared with the number of active lever presses during the 15-min reinstatement session. Group assignment is depicted as follows: control DREADD-expressing rats are shown as black dots, excitatory DREADD-expressing rats are shown as green, and inhibitory DREADD-expressing rats are shown as red.
Tables
Figure location Behavioral test Statistical test used Variables/comparisons Degree of freedom Test value p value 1B Self-administration Two-way ANOVA Session 780 1.8 0.07 Lever 780 349.3 <0.0001 Interaction 780 0.8 0.60 Extinction Two-way ANOVA Session 1092 3.2 <0.001 Lever 1092 103.7 0.0001 Interaction 1092 1.1 0.33 Bonferroni’s post hoc Active vs inactive lever: session 1 1092 5.1 <0.0001 Bonferroni’s post hoc Active vs inactive lever: session 2 1092 4.0 0.0009 Bonferroni’s post hoc Active vs inactive lever: session 3 1092 3.4 0.0096 Bonferroni’s post hoc Active vs inactive lever: session 4 1092 3.2 0.019 Bonferroni’s post hoc Active vs inactive lever: session 5 1092 2.7 0.28 Bonferroni’s post hoc Active vs inactive lever: session 6 1092 3.2 0.02 Bonferroni’s post hoc Active vs inactive lever: session 7 1092 2.4 0.29 Bonferroni’s post hoc Active vs inactive lever: session 8 1092 1.4 0.90 Bonferroni’s post hoc Active vs inactive lever: session 9 1092 2.7 0.10 Bonferroni’s post hoc Active vs inactive lever: session 10 1092 3.1 0.03 Bonferroni’s post hoc Active vs inactive lever: session 10 1092 2.7 0.09 Bonferroni’s post hoc Active vs inactive lever: session 10 1092 1.6 0.82 Bonferroni’s post hoc Active vs inactive lever: session 10 1092 1.7 0.75 Bonferroni’s post hoc Active vs inactive lever: session 10 1092 1.4 0.90 None Self-administration (reinforced vs non-reinforced) Two-way ANOVA Session 740 1.74 0.08 Group (reinforced, non-reinforced) 740 13.6 0.0002 Interaction 740 1.16 0.32 None Self-administration (reinforced vs non-reinforced) Bonferroni’s post hoc Reinforced vs non-reinforced, all sessions 740 0.44–2.22 0.27 to >0.999 2A Self-administration: sex differences, active lever pressing Two-way ANOVA Sex (male, female) 360 1.64 0.20 Session 360 1.30 0.24 Interaction 360 0.33 0.97 2B Self-administration: sex differences, inactive lever pressing Two-way ANOVA Sex (male, female) 360 0.63 0.77 Session 360 8.57 0.004 Interaction 360 0.21 0.99 2B Self-administration: sex differences, inactive lever pressing Bonferroni’s post hoc Male vs female all sessions 360 0.37–1.55 >0.999 2C Self-administration: sex differences, infusions Two-way ANOVA Sex (male, female) 360 0.34 0.56 Session 360 3.47 0.004 Interaction 360 0.31 0.97 2C Self-administration: sex differences, infusions Bonferroni’s post hoc Male vs female: all sessions 360 0.03–1.08 >0.999 2D Self-administration: sex differences, total number of infusions Unpaired Student’s t test Sex (male, female) 36 0.25 0.80 2E Extinction: sex differences, active lever pressing Two-way ANOVA Sex (male, female) 504 2.55 0.11 Session 504 2.28 0.006 Interaction 504 0.75 0.71 2E Extinction: sex differences, active lever pressing Bonferroni’s post hoc Male vs female: all sessions 504 0.02–1.67 >0.999 2F Extinction: sex differences, inactive lever pressing Two-way ANOVA Sex (male, female) 504 5.46 0.02 Session 504 0.70 0.76 Interaction 504 0.48 0.93 2F Extinction: sex differences, inactive lever pressing Bonferroni’s post hoc Male vs female: all sessions 504 0.0007–1.7 0.74 to >0.999 3A Self-administration: DREADD treatment, active lever pressing Two-way ANOVA Treatment (Gs, Gi, control) 350 8.72 0.0002 Session 350 1.21 0.29 Interaction 350 0.56 0.92 3B Self-administration: DREADD treatment, inactive lever pressing Two-way ANOVA Treatment (Gs, Gi, control) 350 6.65 0.002 Session 350 1.04 0.411 Interaction 350 0.65 0.86 3C Self-administration: DREADD treatment, infusions Two-way ANOVA Treatment (Gs, Gi, control) 350 0.57 0.56 Session 350 3.18 0.001 Interaction 350 0.33 0.99 3D Self-administration: DREADD treatment, total number of infusions One-way ANOVA Treatment (Gs, Gi, control) 35 1.25 0.90 3E Extinction: DREADD treatment, active lever pressing Two-way ANOVA Treatment (Gs, Gi, control) 504 12.74 <0.0001 Session 504 2.21 0.008 Interaction 504 0.80 0.75 3F Extinction: DREADD treatment, inactive lever pressing Two-way ANOVA Treatment (Gs, Gi, control) 504 10.52 <0.0001 Session 504 0.67 0.79 Interaction 504 0.21 >0.99 4C Reinstatement Two-way ANOVA Treatment (Gs, Gi, control) 70 8.43 0.0005 Session 70 13.24 0.0005 Interaction 70 6.84 0.0019 4C Bonferroni’s post hoc Control extinction vs control reinstatement 70 4.43 0.0005 4C Bonferroni’s post hoc Gs extinction vs Gs reinstatement 70 2.2 0.03 4C Bonferroni’s post hoc Gi extinction vs Gi reinstatement 70 0.55 0.999 4D A/N ratio Ordinary one-way ANOVA Treatment (Gs, Gi, control) 25 5.7 0.009 4D Bonferroni’s post hoc Control vs inhibitory 25 3.3 0.009 5A Membrane capacitance Ordinary one-way ANOVA Treatment (Gs, Gi, control) 25 0.38 0.69 5B Resting membrane potential Ordinary one-way ANOVA Treatment (Gs, Gi, control) 25 3.3 0.054 5C NMDA decay Ordinary one-way ANOVA Treatment (Gs, Gi, control) 25 5.7 0.009 6 Reinstatement active lever pressing correlation to A/N Linear regression analysis Active lever pressing vs A/N ratio 26 12.37 0.002 Bolded values indicate statistical significance.
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